genenc.hs

data RoseTree a = RTree {
                    rRoot :: a,
                    rBranches :: [RoseTree a] }
  deriving (Show, Eq)

data BinTree a = Branch {
                  broot :: a,
                  bLeft :: (BinTree a),
                  bRight :: (BinTree a) } |
                BLeaf
  deriving (Show, Eq)

listToTree  [] = BLeaf
listToTree (x:xs) =
  let x' = listToTree $ rBranches x
    in Branch (rRoot x) x' (listToTree xs)

roseToBin (RTree r bs) = Branch r (listToTree bs) BLeaf

exampleRose = RTree "A"
  [RTree "B"
    [RTree "H"
      [RTree "N" [], RTree "O" []],
    RTree "I" [],
    RTree "J" []],
  RTree "C" [],
  RTree "D" [],
  RTree "E"
    [RTree "K"
      [RTree "P" []],
    RTree "L"
      [RTree "Q" []]],
  RTree "F" [],
  RTree "G"
    [RTree "M" []]]

main = print $ roseToBin exampleRose